Gas Torch

Abstract

Stoichiometric gas-and-air combinations promoting optimum high-temperature and centered burning in a propane torch or the like are promoted by an air-admitting base member which fixedly mounts a gas nozzle and cooperating venturi in a critical highly-precise spaced concentric alignment which is readily achieved by way of concentrically machined nozzle and venturi seats into which the nozzle and venturi are separately forced into a predetermined centered relationship via alignment-inducing seating surfaces.

Description

BACKGROUND OF THE INVENTION

Gas-burning devices in which ambient air is entrained with a stream of combustible gas to produce a flame-sustaining jet or the like have long been known in a variety of forms, among which is the modern simple torch fitted to a small tank of compressed gas and serving household and professional needs in such operations as soldering and brazing. In some constructions of such torches, a small stream of the compressed gas is sought to be directed centrally into a flame tube by a nozzle having a single very small orifice, the ambient air around the nozzle being admitted to become entrained with the gas and flow with it into the flame tube for mixing which will result in an ignitable jet at the downstream end of the tube. Such an arrangement is disclosed in my U.S. Letters Pat. No. 3,679,171, for example. Preferably, the mixing in the flame tube is improved by a venturi disposed at the upstream end of the tube, and into which the high-velocity nozzle emissions are directed.

It has been found that optimum air-gas mixtures and flame temperatures and efficiency cannot be realized in such torches unless the cooperating nozzle and venturi are very precisely centered, a misalignment or eccentricity of even but a few thousandths of an inch being troublesome. However, the nature of the torch assemblies is necessarily such that the nozzle and venturi must also be held in an axially spaced relation, with needed air being admitted between them, and this poses very practical difficulties, including those associated with costs and skills, in forming precision-related supports for the nozzle and venturi and in assembling them in a required accurate concentricity which can be maintained under conditions of use.

SUMMARY OF THE INVENTION

An elongated tubular torch assembly, having an upstream inlet tube connectable with a compressed-gas source and a downstream flame tube from which an ignitable jet of a gas-air mixture is to be discharged, further includes an intermediate base member which mechanically interconnects the inlet and flame tubes together, which admits ambient air through lateral openings, and which further serves to mount an upstream gas-emitting nozzle and a cooperating downstream venturi in axially spaced and precisely concentric relationships. The latter relationships are uniquely achieved by way of precisely aligned circular machining of axially spaced seats in the base, with the machining preferably being performed simultaneously from one end by a single tool, and by way of cooperating seat surfaces on the nozzle and venturi, respectively, which are to be mounted in relation to the base. The respective mating seating surfaces are shaped to cause automatic centering, and there are further mechanical provisions for keeping the mating seat surfaces together in mechanically secure relationship, whereby the nozzle orifice and venturi opening are reliably held in the desired precise spaced concentric alignment. In the case of one preferred nozzle mounting in the base, the automatic centering is assured by way of a flat-bottomed cylindrical recess in the base, cooperating with a flat-bottomed nozzle which is laterally rounded to press-fit tightly within the cylindrical recess. Cooperating conical mating surfaces assure automatic centering of the base and venturi.

Accordingly, it is one of the objects of the present invention to provide novel and improved gas-burning torches in which optimum flame production is promoted simply and at low cost by self-centering alignments of an orificed nozzle and an associated venturi.

Another object is to provide unique automatic alignment of nozzle and venturi elements of a gas torch by way of cooperating self-centering seating surfaces in a mounting base and on mating portions of the nozzle and venturi elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the aspects of this invention which are considered to be novel are specifically expressed in the appended claims, further details as to preferred practices and embodiments and as to the further objects and features thereof may be most readily comprehended through reference to the following description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a pictorial illustration of a gas torch of a type in which the present invention may be embodied advantageously;

FIG. 2 provides an enlarged and partly cross-sectioned detail of an improved self-centered base, nozzle and venturi assembly in the torch of FIG. 1 and expressing the present invention; and

FIG. 3 provides a similar enlarged and partly cross-sectioned detail of an alternative embodiment of the improved self-centered base, nozzle and venturi assembly in a torch such as that of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Having reference to the drawings, wherein the same reference characters designate identical parts in the different views, and, in the first instance to FIG. 1 thereof, there is illustrated a gas torch 4 of generally elongated form having an inlet tube 5 equipped at its upstream end with a swivel coupling 6 designed to be threadedly connected with the outlet of a pressure-regulator body.7. A suitable regulator is disclosed in my copending U.S. Pat. application Ser. No. 97,107, filed Dec. 11, 1970 and now Pat. No. 3,699,998, for example. A pressurize gas, such as propane, is directed into inlet tube 5 from a tank or the like, through the regulator, and becomes associated with ambient oxygen -- supplying air in a tubular base 8 having lateral air-admitting openings, 9 and 10. In downstream relation to base 8 is a flame tube 11, whence the admixed gas and air are intended to discharge as an ignitable jet which will burn with intense heat and in a rather narrowly defined flame.

Apertured base 8 supports an upstream nozzle element 12 and an axially spaced downstream venturi element 13 which, together, produce a jet-pump action entraining air via the lateral openings 9 and 10 and, further, cause the air and gas to be mixed properly and expelled at high velocity (FIG. 2). Tapered nozzle 12 has an accurately centered minute orifice 14 from which a needle-like stream of the gas is to be directed in as close an axial alignment and centering with the upstream end of venturi 13 as is possible. Skewed or radial divergences between the longitudinal axis of the venturi and the needle-like stream of gas tend to deteriorate the quality of air-gas mixture and lower the temperature of the resulting flame, such that even a few thousandths of an inch or radial eccentricity can prove troublesome in these respects. Although the orificed nozzle and venturi elements themselves can be manufactured quite accurately, their subsequent mounting in the required alignment has been exceedingly difficult to develop and maintain. However, as is shown in FIG. 2, these difficulties are resolved by forming two centered axially spaced circularly machined seats, 15 and 16, in the body of base 8. Upstream annular seat 15 is of right-cylindrical form, with a bottom surface normal to its longitudinal axis, and is of smaller diameters than the downstream conically shaped annular seat 16, such that both seats can be machined in precise axial alignment by a single forming tool inserted from the intended downstream end of the base. Upstream seat 15 is disposed upstream of the lateral base openings 9 and 10, with seat 16 being downstream thereof. Nozzle 12 has a rounded exterior base portion, 12a, generally of ring-like or toroidal curvature, which is of slightly larger maximum diameter than the surrounding inner diameter of the cylindrical portion of seat 15, such that the nozzle may be press-fitted firmly into the illustrated mated relationship with that seat by a suitable tool (not shown) inserted through the downstream end of the base along with the nozzle. An interference of 1-5 thousandths inch is preferred between these mated parts, either or both of which may be of metal such as brass or aluminum. The upstream end of nozzle 12, which is also normal to the longitudinal axis of seat 15, base 8 and the elongated nozzle and its orifice, may be bottomed against the aforesaid bottom surface of seat 15, and the downstream end of that seat may be mechanically punched or peened over to insure accurate seating and holding of the nozzle.

The conical tpaer of downstream seat 16 flares outwardly in the downstream direction, and mates with a correspondingly shaped conically sloped seating surface 17a on the shoulder 17 near the upstream end of the venturi 13. These conical seating surfaces, when fully mated, insure that the longitudinal axis of the venturi is precisely aligned in the critical relationship with the nozzle orifice axis; however, such full mating is realized only when the base and venturi are forced and held together in the illustrated orientation. For the latter purposes, the elongated stainless-steel flame tube 11, closely fitted about the venturi 13, is forced upstream against the venturi shoulder 17 and is firmly held there by a closely surrounding plastic-locking sleeve 18 which, in turn, fits closely within an accommodating cylindrical downstream recess 19 in the base 8. Preferably the locking sleeve 18 is of a plastic such as that commerically known as Delrin, and has a multiplicity of closely spaced annular grooves about its exterior, such that is can cold flow slightly and allow the parts to be snap-fitted together into the illustrated relationship, while thereafter securely holding them in the assembled and properly aligned condition. In other arrangements, screw-threading or other appropriate fastening provisions may serve to hold the base, flame tube and venturi together. A particle filter 20, which assists in avoiding plugging of the small nozzle orifice, is also illustrated upstream of the nozzle, and retained by way of the compression exerted by the screw-threading between the swivel tube 5 and base 8.

In the modification of FIG. 3, wherein the same or functionally corresponding parts are designated by the same reference characters as in FIGS. 1 and 2, with distinguishing single-prime accents being added, the venturi mounting is the same but the nozzle 12' is centered and aligned by way of conically-shaped seating surfaces. There, the exterior surface 12b is conically tapered, with the taper flaring outwardly in the upstream direction, and a correspondingly shaped and sloped annular seat 8b is formed at the upstream part of base 8' to receive and mate with and center the nozzle. Inlet swivel tube 5', when screwed into the illustrated relationship with base 8', securely holds the mating surfaces together and perserves the needed alignment of nozzle 12' and venturi 13'.

Torches of the improved constructions tend to burn with intense heat while nevertheless remaining relatively cool at the site of the base. Aluminum, rather than more costly brass, can be used for the construction of metal parts at the locus of the base, while preserving the needed mechanical integrity and alignments.

Claims

What I claim as new and desire to secure by Letters patent of the United States is:

1. A gas torch including a nozzle having a minute orifice therethrough and a peripheral substantially annular seating surface in concentric alignment with said orifice, a venturi tube having a central passageway which is of relatively small diameter at an upstream end and of outwardly flaring relatively larger diameters downstream thereof, a substantially tubular base member mounting said nozzle and venturi in spaced axial alignment, said base member having a first circularly generated annular seat surface and a second substantially concially shaped annular seat surface concentric with and spaced axially from said first seat surface, said base further having means for admitting gas laterally into the space between said seat surfaces, said venturi tube having an exterior substantially conical seating surface thereon shaped to mate with said second surface, means forcing said conical seating surface of said venturi into mated self-centered relation with said second surface and holding said venturi tube in fixed relation with said base member, said nozzle seating surface being mated with said first seat surface, and means holding said nozzle in fixed relation with said base member with a downstream end of said nozzle orifice in spaced relation to an upstream end of said venturi tube.

2. A gas torch as set forth in claim 1 wherein said base member has lateral orifices admitting air into the space between a downstream end of said nozzle and an upstream end of said venturi tube, and further including an inlet tube for connecting a combustible gas under pressure into said tubular base member at an end upstream of said nozzle, and a flame tube connected with said tubular base member and directing gas-air mixtures downstream thereof and of said venturi tube.

3. A gas torch as set forth in claim 2 wherein said first surface is nearer the upstream end of said base member and is a substantially cylindrical surface, wherein said peripheral seating surface of said nozzle has a substantially spherical rounding and is of a maximum diameter about a few thousandths of an inch larger than that of said cylindrical surface, whereby said peripheral and cylindrical surfaces interfere and said nozzle is thereby tightly fitted with said base when said nozzle peripheral surface is press-fitted to said cylindrical surface.

4. A gas torch as set forth in claim 2 wherein said conical seating surface in said venturi tube is on the upstream side of an external shoulder of said venturi tube, and wherein said means forcing and holding said venturi tube in fixed relation with said base member is in abutting relation to the downstream side of said shoulder.

5. A gas torch as set forth in claim 3 wherein said first surface is of smaller diameter than said second surface and said second annular seat surface has an inner diameter larger than the outer diameter of said first surface, thereby accommodating tooling for the machining of said first surface and for fitting of said nozzle with said first surface through space within said second annular seat surface, said second annular seat surface being nearer the downstream end of said base member and flaring outwardly in the downstream direction.

6. A gas torch as set forth in claim 5 further including a first substantially planar annular surface at the upstream end of said first surface and substantially normal to the central axis of said first surface, and a second substantially planar annular surface at the upstream end of said nozzle disposed to bottom against said first planar surface.

7. A gas torch as set forth in claim 2 wherein said first surface is nearer the upstream end of said base member and is substantially conical, and wherein said peripheral seating surface of said nozzle is substantially conical and sloped to mate with said first surface.

8. A gas torch as set forth in claim 7 wherein said first surface and said nozzle surface flare outwardly in the upstream direction with reference to said base member, and wherein said second surface flares outwardly in the downstream direction.